Options. There are two methods I recommend.
Liners. One is to use paper cupcake liners. This is the best of the two options and makes cleanup a breeze. However, I don't always have them on hand.
12-16 paper cupcake liners
Butter. The other is to use a paper towel to spread butter on the bottoms and sides of each cupcake well. Then, sprinkle a bit of flour in the bottom of each well. Tap the pan to shake the flour so that if covers the bottoms entirely. Next, (over the sink) turn the pan on its side, and rotate the whole pan, tapping as needed, to move the flour until all sides of the wells are covered in flour. Tap out any excess flour.
2 tablespoons butter (for greasing pan), 1/4 cup flour (for greasing pan)
Fill. Fill each well ¾ of the way full with batter. This is about ¼ cup. I fill a measuring cup and use a spoon to get the batter out of the measuring cup and into the well. If you are using paper liners, be sure to pour into the center to avoid pulling the liner in and getting wonky.
Bake. Bake for 20 minutes. Put a toothpick in the middle of a cupcake. It should come out nearly clean, a few crumbs sticking is ok. Wet batter sticking is not. If this happens, bake for 1-2 minutes more, and check again.
Cool. I recommend removing the cupcakes from the pan and let them cool on a wire rack. The pan is hot, and it will take longer for the cupcakes to cool if they remain in the pan.
Really Cool The cupcakes should be completely cooled before frosting. If they are hot/warm, the frosting will melt right off. Yikes.